Unity shader实现自由放大缩小效果

Shader "Hidden/Wave"
{
 Properties
 {
 _MainTex ("Texture", 2D) = "white" {}
 _WaveWidth("Wave Width",float) = 0.5
 _CenterX("CenterX",float)=0.5
 _CenterY("CenterY",float)=0.5
 }
 SubShader
 {
 // No culling or depth
 Cull Off ZWrite Off ZTest Always

 Pass
 {
  CGPROGRAM
  #pragma vertex vert
  #pragma fragment frag
  
  #include "UnityCG.cginc"

  struct appdata
  {
  float4 vertex : POSITION;
  float2 uv : TEXCOORD0;
  };

  struct v2f
  {
  float2 uv : TEXCOORD0;
  float4 vertex : SV_POSITION;
  };


  float _WaveWidth;
  float _CenterX;
  float _CenterY;
  v2f vert (appdata v)
  {
  v2f o;
  o.vertex = UnityObjectToClipPos(v.vertex);
  o.uv = v.uv;
  return o;
  }
  
  sampler2D _MainTex;

  fixed4 frag (v2f i) : SV_Target
  {
  float2 center=float2(_CenterX,_CenterY);
  float2 distance= center - i.uv;
  float x=center.x+ center.x*(-distance.x/center.x) *(1-_WaveWidth);
  float y=center.y+ center.y*(-distance.y/center.y) *(1-_WaveWidth);
  float2 uv = float2(x,y);
  return tex2D(_MainTex, uv);  
  }
  ENDCG
 }
 }
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
 
public class WaveCreame : MonoBehaviour {
 
 
  public Shader waveShader = null;
  [Range(0.0f,1f)]
  public float waveWidth = 0.3f;
  private Material m_WaveMaterial = null;
  private float m_CenterX = 0.5f;
  private float m_CtenterY = 0.5f;
 // Use this for initialization
 void Start () {
    m_WaveMaterial = new Material(waveShader);
 }
 
 // Update is called once per frame
 void Update () {
    Vector3 pos = Input.mousePosition;
    m_CenterX = pos.x / Screen.width;
    m_CtenterY = pos.y / Screen.height;
    if (Input.GetMouseButton(0)) {
      waveWidth += Time.deltaTime * 0.5f;
    }
    if (Input.GetMouseButton(1))
    {
      waveWidth -= Time.deltaTime * 0.5f;
    }
  }
 
  private void OnRenderImage(RenderTexture source, RenderTexture destination)
  {
    if (waveShader == null || m_WaveMaterial == null) return;
    m_WaveMaterial.SetFloat("_WaveWidth", waveWidth);
    m_WaveMaterial.SetFloat("_CenterX", m_CenterX);
    m_WaveMaterial.SetFloat("_CenterY", m_CtenterY);
    Graphics.Blit(source, destination, m_WaveMaterial);
  }
}